An improved experimental design for studying the enterohepatic circulation of drugs in a pair of bile duct-duodenum cannula-linked rats is described. By housing the rats in individual metabolism cages and using a peristaltic pump to immediately deliver bile secreted by the donor directly into the duodenum of the recipient, the method permits a realistic approximation of biliary excretion and reabsorption in intact animals for periods up to 96 hours.